Holder, fusion-splicing apparatus, and manufacturing method of optical connector

ABSTRACT

A holder capable of protecting an optical connector ferrule from an external shock, or the like and executing a fusion-splice of a short optical fiber not to take out the optical connector ferrule from the holder is obtained. 
     A holder for holding a connector plug equipped with an optical connector ferrule to which a short optical fiber is fitted and a plug frame for covering an outer periphery of the optical connector ferrule therein, wherein, when the short optical fiber together with the holder is fitted to a fusion splicing apparatus that fusion-splices the short optical fiber and other coated optical fiber, the short optical fiber extended from the plug frame is positioned in a fusion position.

TECHNICAL FIELD

The present invention relates to a holder for housing a connector plughaving an optical connector ferrule with a short optical fiber toprotect it, a fusion splicing apparatus for fusion-splicing the shortoptical fiber and other coated optical fiber, and an optical connectorassembling method of assembling an optical connector by using the holderand the fusion splicing apparatus.

RELATED ART

In the private optical wiring, etc., the optical connector must befitted to the optical fiber cable in the field.

In the prior art, as one mode of the structure that the opticalconnector ferrule is connected to the end of the coated optical fiber inthe field, there is an optical connector 110 set forth in PatentLiterature 1 (FIG. 25).

In the optical connector 110 shown herein, a short optical fiber 103fitted to an optical connector ferrule 102 previously are connected to acoated optical fiber 100 in the field by the fusion splice, and thecircumference of a fusion spliced portion 105 is covered with aprotection sleeve 101 and is reinforced.

This optical connector 110 is constructed such that a connector housing121 houses respective elements from the optical connector ferrule 102 toa part of the coated optical fiber 100 located in the rear of theprotection sleeve 101 that covers the fusion spliced portion 105therein.

Here, the connector housing 121 is constructed to have a plug frame 122for housing the optical connector ferrule 102 in a state that its topend is projected, a boot 123 for housing an end portion of the coatedoptical fiber 100, and a cylindrical stop ring 124 one end of which isfitted integrally into the plug frame 122 and the other end of which isfitted integrally into the boot 123. Also, the optical connector ferrule102 in the plug frame 122 is energized to the top end side by acompression coil spring 125. This compression coil spring 125 enablesthe optical connector ferrule 102 to move back in connecting theconnector such that a contact pressure between the optical connectorferrule 102 and the optical connector ferrule of the opposing opticalconnector can be kept within a normal range.

[Patent Literature 1] JP-A-2002-82257

The optical connector ferrule 102 used in the optical connector 110needs delicate handling. This is because it should be prevented that theshort optical fiber 103 extended from the optical connector ferrule 102is damaged due to the bending action caused in carrying, holding, etc.the ferrule in the site.

Therefore, for the purpose of protecting the optical connector ferrule102 and the short optical fiber 103 in carrying, holding, etc. theferrule in the site, utilization of the housing case for housing/holdingthese elements may be thought of.

However, even though the housing case is employed, the optical connectorferrule 102 must be taken out from the housing case and then set to thefusion splicing apparatus prepared in the field in advance when othercoated optical fiber 100 is fusion-spliced to the short optical fiber103 in the field. As a result, it is feared that the optical connectorferrule 102 or the short optical fiber 103 is broken down during thehandling needed until the optical connector ferrule 102 is set to thefusion splicing apparatus.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a holder capable ofprotecting an optical connector ferrule with a short optical fiber froman external shock, or the like and aligning the short optical fiber witha fusion position of a fusion splicing apparatus while holding theoptical connector ferrule therein, a fusion splicing apparatus equippedwith a fusion processing portion to which the holder that is holding theoptical connector ferrule can be fitted and a thermal shrinkageprocessing portion for causing a thermal shrinkable tube that coversfusion-spliced portions of mutual optical fibers to thermally shrink,and an optical connector assembling method capable of assemblingeffectively an optical connector by using the holder and the fusionsplicing apparatus.

The present invention solves the above problems by employing followingconfigurations in [1] to [14].

[1] A holder for containing an optical connector ferrule to which ashort optical fiber is fitted, wherein the holder is constructed toposition the short optical fiber extended from the optical connectorferrule and to be fitted to a fusion splicing apparatus thatfusion-splices the short optical fiber and other coated optical fiber.

[2] In the holder according to [1], a recess portion for positioning theshort optical fiber extended from the optical connector ferrule isprovided.

[3] In the holder according to [1], a lid member for pressing theoptical connector ferrule is provided to a holder main body in which aferrule containing portion for containing the optical connector ferruleis formed.

[4] In the holder according to [3], the lid member is formed oftransparent material.

[5] In the holder according to [1], the optical connector ferrule towhich the short optical fiber is fitted is contained in a mode of aconnector plug whose outer periphery is covered with a plug frame.

[6] In the holder according to [5], a V groove for positioning the shortoptical fiber extended from the plug frame is provided.

[7] In the holder according to [5], a lid member for pressing the plugframe is provided to a holder main body on which a plug housing portionfor housing the plug frame therein is formed.

[8] In the holder according to [7], the lid member is formed of atransparent material.

[9] In the holder according to [7], the lid member presses the shortoptical fiber positioned on the V groove.

[10] A fusion splicing apparatus for fusion-slicing a short opticalfiber fitted to an optical connector ferrule and other coated opticalfiber, which includes a fusion processing portion equipped with a holderfitting portion that fits the holder according to [1].

[11] In the fusion splicing apparatus according to [10], the fusionsplicing apparatus further includes a thermal shrinkage processingportion for heating/shrinking a thermal shrinkable tube that is put onan outer periphery of a fusion spliced portion being formed by thefusion processing portion; wherein the thermal shrinkage processingportion is equipped with a holder fitting portion that fits the holder.

[12] In the fusion splicing apparatus according to [11], the thermalshrinkage processing portion has a first thermal shrinkage processingportion in which a heating temperature distribution is set such that aheating temperature of the thermal shrinkable tube on the short opticalfiber side is higher than that on the coated optical fiber side.

[13] In the fusion splicing apparatus according to [12], the thermalshrinkage processing portion has a second thermal shrinkage processingportion in which a heating temperature distribution is set such that aheating temperature of the thermal shrinkable tube on a middle portionside is higher than that on an end portion.

[14] An optical connector assembling method of assembling an opticalconnector in which other coated optical fiber is fusion-spliced to ashort optical fiber, by fusion-splicing the short optical fiber beingfitted to an optical connector ferrule to the other coated optical fiberwhile using the fusion splicing apparatus according to [10], whichincludes a step of setting the coated optical fiber on a fiber fittingportion of a fusion processing portion of the fusion splicing apparatus;a step of setting a holder that holds a connector plug therein in aholder fitting portion of the fusion processing portion; a step offusion-splicing the short optical fiber positioned in the holder that isfitted to the holder fitting portion and the coated optical fiberpositioned in the fiber fitting portion in the fusion processingportion; a step of forming a fusion spliced portion by fusion-splicingthe short optical fiber and the coated optical fiber, and then putting aprotection sleeve having a thermal shrinkable tube on the fusion splicedportion; and a step of transferring the fusion spliced portion to thethermal shrinkage processing portion, and then heating the thermalshrinkable tube of the protection sleeve to shrink.

According to the holder of the present invention, when the plug framefitted onto the optical connector ferrule to which the short opticalfiber is fitted is housed in the holder, this holder can protect theoptical connector ferrule and the short optical fiber from a shock, etc.applied from the outside.

In addition, this holder can position the short optical fiber beingfitted into the optical connector ferrule in a fusion position of thefusion splicing apparatus while holding the plug frame therein.Therefore, the troublesome operation of taking out the connector plugfrom the holder in the fusion splice can be omitted, and thus the easyhandling property at a time of fusion splice can be improved.

According to the fusion splicing apparatus of the present invention, thefusion processing portion equipped with the holder fitting portion towhich the holder can be fitted is provided. As a result, the shortoptical fiber being fitted into the optical connector ferrule can befusion-spliced to the other coated optical fiber not to pick up theoptical connector ferrule from the holder, and the operability in thefusion-splicing operation can be improved.

Also, because the thermal shrinkage processing portion for causing thethermal shrinkable tube that covers the fusion-spliced portions ofmutual fibers to thermally shrink is provided in parallel with thefusion processing portion, the thermally shrinking process of thethermal shrinkable tube can be applied not to take out the connectorplug from the holder.

According to the optical connector assembling method of the presentinvention, the optical connector can be assembled effectively by usingthe holder and the fusion splicing apparatus without damage of theoptical connector ferrule and the short optical fiber.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 A perspective view of a first embodiment of a holder according tothe present invention.

FIG. 2 A perspective view showing a state that a cap is fitted onto theholder shown in FIG. 1.

FIG. 3 A perspective view showing a state that a lid member of theholder shown in FIG. 1 is closed.

FIG. 4 A sectional-view when viewed from an arrow A in FIG. 3.

FIG. 5 A perspective view of a second embodiment of a holder accordingto the present invention.

FIG. 6 A perspective view showing a state that a lid member of theholder shown in FIG. 5 is opened.

FIG. 7 A perspective view of an embodiment of a fusion splicingapparatus according to the present invention when viewed from obliquelyabove.

FIG. 8 An enlarged view of a fusion processing portion of the fusionsplicing apparatus in FIG. 7.

FIG. 9 An enlarged view showing a state that a cover of a thermalshrinkage processing portion of the fusion splicing apparatus in FIG. 7.

FIG. 10 A perspective exploded view showing a schematic configuration ofan optical connector that is assembled by using the fusion splicingapparatus in FIG. 7.

FIG. 11 A perspective exploded view of a connector plug shown in FIG.10.

FIG. 12 A perspective exploded view of a protection sleeve and a rearhousing shown in FIG. 10.

FIG. 13 An enlarged side view of the protection sleeve shown in FIG. 12.

FIG. 14 A sectional view taken along a B-B line in FIG. 13.

FIG. 15 An explanatory view of procedures of an optical connectorassembling method according to the present invention.

FIG. 16 A longitudinal sectional view of the optical connector that iscompleted by the optical connector assembling method in FIG. 15.

FIG. 17 An exploded side view of an optical connector used in a thirdembodiment of the present invention.

FIG. 18 (a) is a longitudinal sectional view of the optical connectorshown in FIG. 17, and (b) is a longitudinal sectional view of apertinent portion of a variation in which a reinforcing tube is fitted.

FIG. 19 (a) is a sectional view of an optical connector ferrule shown inFIG. 20, and (b) is a longitudinal sectional view of a thermalshrinkable tube connected to the optical connector ferrule.

FIG. 20 A perspective view of a third embodiment of the holder accordingto the present invention.

FIG. 21 A plan view showing a state that a lid member of the holdershown in FIG. 20 is closed.

FIG. 22 A front view of the holder shown in FIG. 21.

FIG. 23 A perspective view of a fusion splicing apparatus according tothe present embodiment when viewed from the obliquely above side.

FIG. 24 An enlarged view of the fusion splicing apparatus in FIG. 23 ina state that a cover of a thermal shrinkage processing portion isremoved.

FIG. 25 An explanatory view of a fusion splicing structure in the priorart.

DESCRIPTION OF REFERENCE NUMERALS AND SIGNS

-   1 optical connector-   3 coated optical fiber-   5 short optical fiber-   7 optical connector ferrule-   9 plug frame-   9 a diameter-contracted portion-   9 b engaging groove-   10 connector plug-   11 stopper-   13 fusion spliced portion-   15 protection sleeve-   17 internal space-   19 structural body-   21 boot-   22 dust cap-   23 ferrule press spring-   25 thermal shrinkable tube-   27 core rod-   29 adhesive tube-   31 coupling component-   33 SC connector knob-   35 space-   37 reinforcing tube-   51 holder-   53 plug housing portion-   54 holder main body-   56 lid member-   58 rotation supporting shaft-   61 V groove-   63 holder-   71 fusion splicing apparatus-   73 holder fitting portion-   74 fusion processing portion-   76 thermal shrinkage processing portion-   78 fiber fitting portion-   79 V-groove member-   81 V-groove member-   83 electrode-   86 first thermal shrinkage processing portion-   87 second thermal shrinkage processing portion

BEST MODE FOR CARRYING OUT THE INVENTION

Respective preferred embodiments will be explained in detail in order ofa holder, a fusion splicing apparatus, and an optical connectorassembling method according to the present invention with reference tothe drawings hereinafter.

FIG. 1 is a perspective view of a first embodiment of a holder accordingto the present invention, wherein a lid member is opened.

FIG. 2 is a perspective view showing a state that a cap is fitted ontothe holder shown in FIG. 1. FIG. 3 is a perspective view showing a statethat a lid member of the holder shown in FIG. 1 is closed. FIG. 4 is aschematic view when viewed from an arrow A in FIG. 3.

A holder 51 of the first embodiment holds a connector plug 10 in which astopper 11 is fitted into a plug frame 9, into which an opticalconnector ferrule 7 (see FIG. 11) described later is fitted, and onwhich a dust cap 22 is fitted. Thus, the holder 51 protects a shortoptical fiber 5 fitted to the optical connector ferrule 7 previously andthe connector plug 10.

In the holder 51 of the first embodiment, a foldable lid member 56 isfitted to a holder main body 54 on which a plug housing portion 53 as arecess for housing the plug frame 9 therein is formed to open upward.The foldable lid member 56 covers the plug housing portion 53 to holdthe plug frame 9 contained in the plug housing portion 53.

As indicated with a chain double-dashed line in FIG. 2, a box-type cap57 is detachably attached to the front end side of the holder main body54 from which the short optical fiber 5 is extended. This box-type cap57 covers the surrounding of the short optical fiber extended from theholder main body 54 to protect the short optical fiber 5 and the plugframe 9.

The cap 57 may be formed of the antistatic material.

The lid member 56 is hinged to the rear end portion of the holder mainbody 54 via a pivot 58 that is fitted into the rear end side of theholder main body 54. The lid member 56 when turned around the pivot 58is opened/closed in the arrow a direction shown in FIG. 1.

The lid member 56 is shaped into an almost planar shape that covers theholder main body 54. As shown in FIG. 3, a grasping portion 56 a beingheld by worker's fingers in opening/closing operations is provided toboth sides respectively to project therefrom.

Also, as shown in FIG. 3, a window hole 56 b through which the workercan view the based end portion and its periphery of the plug frame 9housed in the holder main body 54 is formed in the lid member 56 to passtherethrough.

In the holder 51 of the first embodiment, as shown in FIG. 4, a V groove61 is provided to an upper end surface of a front end wall 54 a of theholder main body 54 through which the short optical fiber 5 passes.Thus, this V groove 61 positions and supports the short optical fiber 5extended from the plug frame 9.

Also, as shown in FIG. 4, the lid member 56 when is closed presses theshort optical fiber 5 being positioned in the V groove 61 against thefront end wall 54 a.

In this manner, the holder main body 54 on which the plug housingportion 53 is formed, the V groove 61 formed on the holder main body 54,and the lid member 56 for pressing the short optical fiber 5 to the Vgroove 61 are provided to the holder 51. Then, the holder 51 is fittedto a fusion splicing apparatus 71 that fusion-splices the short opticalfiber 5 and other coated optical fiber 3 (see FIG. 8) in the field,described later. At that time, the holder 51 can position as it is theshort optical fiber 5 extended from the plug frame 9, which is housed inthe plug housing portion 53, in a fusion position.

According to the holder 51 of the first embodiment explained above, whenthe plug frame 9 fitted onto the optical connector ferrule 7, to whichthe short optical fiber 5 is fitted in advance, is housed in the holder51, this holder 51 can protect the optical connector ferrule 7 and theshort optical fiber 5 from a shock, etc. applied from the outside andalso facilitate the handling in carrying, holding, etc. the ferrule inthe site.

Also, while holding the plug frame 9 therein, the holder 51 can positionthe short optical fiber 5 being fitted into the optical connectorferrule 7 in a fusion position of the fusion splicing apparatus 71.Therefore, the troublesome operation of taking out the connector plug 10from the holder 51 in the fusion splice can be omitted, and thus theeasy handling property at a time of fusion splice can be improved.

In addition, if this holder 51 can be fitted to the fusion splicingapparatus that connects the existing coated optical fibers mutually,there is no need to prepare the dedicated fusion splicing apparatus.

Also, in the holder 51 of the first embodiment, the V groove 61 forpositioning and supporting the short optical fiber 5 extended from theplug frame 9 is provided, and also the short optical fiber 5 extendedfrom the optical connector ferrule 7 that is housed in this holder 51 ispositioned precisely on the holder 51 by an action of the V groove 61.Therefore, when the holder 51 is set to the fusion splicing apparatus71, no time and labor to position the short optical fiber 5 is needed.

Also, the holder 51 of the first embodiment is constructed by providingthe lid member 56, on which the plug housing portion 53 for housing theplug frame 9 therein is formed to open upward, to the holder main body54 that covers the plug housing portion 53 to press the plug frame 9held in the plug housing portion 53. Therefore, loading/unloading of theplug frame 9 into/from the holder 51 can be executed easily byopening/closing the foldable lid member 56.

Also, in the holder 51 of the first embodiment, not only the V groove 61for positioning/supporting the short optical fiber 5 is provided to theholder main body 54 on which the plug housing portion 53 that holds theplug frame 9 is formed to open upward, but also the lid member 56presses the short optical fiber 5 positioned in the V groove 61.

Accordingly, the short optical fiber 5 extended from the plug frame 9that is housed in the holder main body 54 is positioned by the V groove61, and then is fixed to the V groove 61 by the lid member 56.Therefore, the positioning of the short optical fiber 5 can be executedwithout fail.

In addition, it is preferable that a projection portion should beprovided to the lid member 56 on the side that is closer to the end ofthe short optical fiber 5 than the V groove 61 in such a way that thisprojection portion presses the short optical fiber 5 toward the V groove61 from the upper side and the short optical fiber 5 is directedobliquely below. This is because, even when the short optical fiber 5got kinked, or the like, such short optical fiber 5 is corrected alongthe V groove 61 and is ready to be positioned in the fusion splice.

Also, the window hole 56 b through which the worker can view the basedend portion and its periphery of the plug frame 9 is formed in the lidmember 56. Therefore, unless the worker does not open the lid member 56,such worker can check holding condition, type, etc. of the plug frame 9being housed.

In the first embodiment, the window hole 56 b is provided in the lidmember 56 to facilitate the viewing of the plug frame 9 being housed inthe holder main body 54. In this case, instead of the provision of thewindow hole 56 b, the lid member 56 may be formed of the transparentmaterial. When the lid member 56 is formed of the transparent materialin this manner, the worker can check the held plug frame 9 with his orher eyes not to open the lid member 56.

In this case, in the holder according to the present invention, thecoupling position of the holder main body 54 and the lid member 56 andthe opening/closing direction of the lid member 56 are not restricted tothe configurative modes shown in the first embodiment.

FIG. 5 is a perspective view of a second embodiment of a holderaccording to the present invention, wherein the foldable lid member isclosed in a state that the cap is removed. FIG. 6 is a perspective viewshowing a state that the lid member of the holder shown in FIG. 5 isopened.

A holder 63 shown herein is common to the first embodiment in that theholder main body 54 having the plug housing portion 53, which housestherein the plug frame 9 that is fitted onto the optical connectorferrule 7 described later (see FIG. 11) while the dust cap 22 and thestopper 11 are fitted to this plug frame 9, and the lid member 56provided foldably to the holder main body 54 to cover the plug housingportion 53 are provided.

However, in the case of this holder 63, the fitting position and theopening/closing direction of the lid member 56 are improved. In the caseof this holder 63, as indicated by an arrow b in FIG. 6, the lid member56 can be opened/closed sideward on the pivot 58 that is fitted into theside end portion of the holder main body 54.

In this manner, the fitting position and the opening/closing directionof the lid member 56 can be changed in design appropriately in responseto the holder main body 54 that houses the plug frame 9.

Next, an embodiment of a fusion splicing apparatus according to thepresent invention will be explained hereunder.

FIG. 7 is a perspective view of an embodiment of a fusion splicingapparatus according to the present invention when viewed from obliquelyabove. FIG. 8 is an enlarged view of a fusion processing portion of thefusion splicing apparatus in FIG. 7. FIG. 9 is an enlarged view showinga state that the cover of the thermal shrinkage processing portionprovided to the fusion splicing apparatus in FIG. 7.

The fusion splicing apparatus 71 shown in FIG. 7 to FIG. 9 is such anapparatus that fusion-splices the short optical fiber 5 being fitted tothe optical connector ferrule 7 to other coated optical fiber 3 in thesite where the construction work to lay the optical fiber cable iscarried out.

This fusion splicing apparatus 71 is equipped with a fusion processingportion 74 into which a holder fitting portion 73 fits the short opticalfiber 5 housed in the holder 51 together with the holder 51 to positionthe fiber in a fusion position to the other coated optical fiber 3 isinstalled, and a thermal shrinkage processing portion 76 for thermallyshrinking a thermal shrinkable tube 25 coated on an outer periphery of afusion spliced portion 13 (see FIG. 13), which fusion-splices the shortoptical fiber 5 being fusion-spliced by the fusion processing portion 74to the other coated optical fiber 3, by a heater.

The fusion processing portion 74 is provided to an upper surface portionof the apparatus that is covered with a foldable cover 77.

As shown in FIG. 8, the fusion processing portion 74 has a fiber fittingportion 78 for setting the other coated optical fiber 3 in the site, aV-groove member 79 arranged at the top end of the fiber fitting portion78 to position a top end position of the coated optical fiber 3 beingset on the fiber fitting portion 78, a V-groove member 81 forpositioning a top end position of the short optical fiber 5 extendedfrom the holder 51 being set to the holder fitting portion 73, and apair of electrodes 83 arranged to the V-groove members 79, 81respectively to fusion-weld mutual butted optical fibers by the electricdischarge.

Dimensions of the V-groove member 81 for positioning the short opticalfiber 5 and the V groove 61 of the holder 51 being set in the holderfitting portion 73 are set to support/align the short optical fiber 5 ona straight line.

The holder 51 may be fitted previously in the holder fitting portion 73.In this case, the worker picks up the connector plug 10 housed inanother case and then puts this plug in the holder 51 being set in theholder fitting portion 73.

The thermal shrinkage processing portion 76 has a particular foldablecover 84, and equipped adjacently to the fusion processing portion 74.

As shown in FIG. 9, when the foldable cover 84 is opened, two thermalshrinkage processing portions of a first thermal shrinkage processingportion 86 and a second thermal shrinkage processing portion 87 providedin parallel appear.

The first and second thermal shrinkage processing portions 86, 87 have adifferent heating temperature distribution described later respectively,but both portions are formed in the same configuration. Therefore, onlythe first thermal shrinkage processing portion 86 will be explainedherein.

The first thermal shrinkage processing portion 86 is equipped with aheating portion 88 to which a heater (not shown) for heating the thermalshrinkable tube 25 is provided, a holder fitting portion 89 forpositioning/fitting the holder 51 that contains the connector plug 10,and a fiber-fitting portion 90.

Although omitted from the holder fitting portion 89 in FIG. 9, afoldable cover 91 for inhibiting the coming-out of the coated opticalfiber and the plug frame 9 is fitted to the holder fitting portion 89and the fiber fitting portion 90 respectively.

In the first thermal shrinkage processing portion 86, a heatingtemperature distribution of the heater is set such that a heatingtemperature of the thermal shrinkable tube 25 on the short optical fiber5 (the connector plug 10) side is higher than that on the coated opticalfiber 3 side.

In the second thermal shrinkage processing portion 87, a heatingtemperature distribution of the heater is set such that a heatingtemperature of the thermal shrinkable tube 25 on the middle portion sideis higher than that on the end portion.

The first thermal shrinkage processing portion 86 is the configurationthat is suitable for a protection sleeve 15 in which an end portion ofthe thermal shrinkable tube 25 is connected to a coupling component 31,or the like described later. The heating temperature distribution isgiven to the heater such that first the short optical fiber side isheated to cause the shrinkage and then the other optical fiber side isheated to cause the shrinkage. Therefore, voids generated in the thermalshrinkable tube 25 at a time of heating are ready to come out of the endportion on the other optical fiber side.

Also, if the second thermal shrinkage processing portion 87 is provided,the heating process can be applied even when the ordinary coated opticalfibers are to be connected mutually. In this case, the heatingtemperature distribution is given to the heater such that the centerportion of the thermal shrinkable tube 25 is heated at a hightemperature to cause the shrinkage and then the end portion is heated tocause the shrinkage. Therefore, voids generated in the thermalshrinkable tube 25 at a time of heating are ready to come out of bothend portions.

The fusion splicing apparatus 71 explained above is equipped with thefusion processing portion 74 into which the holder fitting portion 73 towhich the holder 51 that housed the optical connector ferrule 7 thereincan be fitted is installed. As a result, the short optical fiber 5 beingfitted into the optical connector ferrule 7 can be fusion-spliced to theother coated optical fiber 3 not to pick up the optical connectorferrule 7 from the holder 51, and the operability in the fusion-splicingoperation can be improved.

Also, because the thermal shrinkage processing portion 76 for causingthe thermal shrinkable tube 25 that covers the fusion-spliced portionsof mutual fibers to thermally shrink is provided in parallel with thefusion processing portion 74, the thermally shrinking process of thethermal shrinkable tube 25 can be applied quickly on the same fusionsplicing apparatus 71. In this case, because the thermal shrinkageprocessing portion 76 is equipped with the holder fitting portion 89, towhich the holder 51 that held the connector plug 10 therein can befitted, similarly to the holder fitting portion 73 in the fusionprocessing portion 74, the thermal shrinkable tube 25 on the fusionspliced portion 13 extended from the holder 51 can be thermally shrunkat an adequate heating temperature distribution by arranging/positioningthe holder 51 in the holder fitting portion 89 after the fusion process.

Also, because the second thermal shrinkage processing portion 87 havinga heating temperature distribution already described is provided, onefusion splicing apparatus can be used commonly in the connection betweenthe short optical fiber having the connector plug and the other coatedoptical fiber, the fusion splice between the coated optical fibers, andthe heating process of the thermal shrinkable tube after both fibers areconnected. Therefore, there is no necessity to prepare the dedicatedfusion splicing apparatus.

In addition, in the case of the fusion splicing apparatus 71, twothermal shrinkage processing portions 76 each having a different heatingtemperature distribution of the heater that heats the thermal shrinkabletube 25 are provided as the thermal shrinkage processing portion 76.Therefore, the heating process to meet the fitting mode of the thermalshrinkable tube 25 can be carried out by selecting either of the thermalshrinkage processing portions 76.

In respective embodiments of the holder, such a configuration is shownthat the lid member is fitted to the holder main body. However, thefoldable cover of the fusion splicing apparatus can be used commonly asthis lid member.

Next, an optical connector assembling method according to the presentinvention will be explained with reference to FIG. 10 to FIG. 14 andFIG. 16 hereunder.

FIG. 10 is a perspective exploded view showing a schematic configurationof the optical connector that is assembled by using the fusion splicingapparatus in FIG. 7. FIG. 11 is a perspective exploded view of aconnector plug shown in FIG. 10. FIG. 12 is a perspective exploded viewof a protection sleeve and a rear housing shown in FIG. 10. FIG. 13 isan enlarged side view of the protection sleeve shown in FIG. 12. FIG. 14is a sectional view taken along a B-B line in FIG. 13. FIG. 15 is anexplanatory view showing procedures of the optical connector assemblingmethod according to the present invention. FIG. 16 is a longitudinalsectional view of the optical connector that is completed by the opticalconnector assembling method in FIG. 15.

An optical connector 1 is fitted to the end portion of the coatedoptical fiber 3 in the field. As shown in FIG. 10, the optical connector1 includes the connector plug 10 in which the optical connector ferrule7 is fitted into the plug frame 9, an SC connector knob 33 fitted ontothe outer periphery of the connector plug 10, the protection sleeve 15for covering the circumference of the fusion spliced portion 13 (seeFIG. 13) between the short optical fiber 5 fitted to the opticalconnector ferrule 7 and the coated optical fiber 3 in the field, a rearhousing 18 which has an internal space 17 in which the protection sleeve15 is arranged and whose top end is coupled integrally to the plug frame9, and a boot 21 which houses the end portion and its neighborhood ofthe coated optical fiber 3 being fusion-spliced to the short opticalfiber 5 therein to protect the coated optical fiber 3 and whose top endis coupled integrally to the base end of the rear housing 18.

As shown in FIG. 11, the connector plug 10 has the optical connectorferrule 7 to which the short optical fiber 5 is fitted in advance, theplug frame 9 that houses/holds the optical connector ferrule 7, thealmost cylindrical stopper 11 which is fitted into the opening of theplug frame 9 on the base end side and into which the optical connectorferrule 7 is inserted, a ferrule press spring 23 fitted between thestopper 11 and a diameter-enlarged portion 7 b of the optical connectorferrule 7 in its compressed mode to support elastically the opticalconnector ferrule 7 in the plug frame 9 to retreat, and the dust cap 22fitted to the top end side of the plug frame 9 to cover a top end shaftportion 7 a of the optical connector ferrule 7 projected from the topend of the plug frame 9.

The connector plug 10 is contained/held in the above holders 51, 63.

The optical connector ferrule 7 has such a shape that thediameter-enlarged portion 7 b whose diameter is enlarged is provided atthe back of the top end shaft portion 7 a that is butt-connected to theopposing optical connector ferrule. The short optical fiber 5 is fittedsuch that its center axis agrees with the top end shaft portion 7 a.Also, as shown in FIG. 11, a sleeve coupling projection 7 c to which theprotection sleeve 15 is coupled is provided on the outer periphery ofthe optical connector ferrule 7 on the base end side from which theshort optical fiber 5 is protruded.

When the optical connector ferrule 7 is inserted into opening on thebasal end side of the plug frame 9, the front end of thediameter-enlarged portion 7 b contacts a diameter-contracted portion 9 aprojected from the inner periphery of the plug frame 9 to restrict itsforward movement, as shown in FIG. 16. In this condition, as shown inFIG. 16, a position of the optical connector ferrule 7 is restrictedsuch that the top end of the optical connector ferrule 7 is protrudedfrom the top end of the plug frame 9 by a predetermined length L1.

Then, as described above, in order to prevent that a dust, and the likeadhere to the fiber end surface in keeping the optical fiber, and thelike, the dust cap 22 is put on the top end of the optical connectorferrule 7 that is positioned in the plug frame 9.

As shown in FIG. 13, the fusion spliced portion 13 is formed by causingan uncoated portion 5 b from which a coating 5 a in the end portion ofthe short optical fiber 5 is peeled off and an uncoated portion 3 b fromwhich a coating 3 a in the end portion of the coated optical fiber 3 ispeeled off to butt to each other, and then fusion-splicing the buttedfiber end surfaces mutually.

As shown in FIG. 12 to FIG. 14, the protection sleeve 15 has the thermalshrinkable tube 25, a core rod 27 passed through the thermal shrinkabletube 25 and an adhesive tube 29, and the coupling component 31 securedto one end of the thermal shrinkable tube 25. The coupling component 31is coupled to the optical connector ferrule 7.

The thermal shrinkable tube 25, when heated up to a predeterminedtemperature by the heater, causes the thermal shrinkage and is tightlyadhered to the core rod 27 passing therethrough.

As shown in FIG. 13 and FIG. 14, the core rod 27 is a solid round rodwhose cross sectional shape is a circle, and is passed through thethermal shrinkable tube 25 as a reinforcing core material. As the corerod 27, a steel wire, a glass, and the like can be employed.

The adhesive tube 29 is the tube that is made of an adhesive agent andis inserted into the thermal shrinkable tube 25 along with the core rod27 longitudinally. The adhesive tube 29 is softened by the heating beingapplied in thermally shrinking the thermal shrinkable tube 25, and actsas an adhesive to fill a clearance 34 between the thermal shrinkabletube 25 and the core rod 27 shown in FIG. 14.

The protection sleeve 15 positions at first the thermal shrinkable tube25, the core rod 27, and the adhesive tube 29 in a state that the endportion of the core rod 27 and the end portion of the adhesive tube 29protrude from one end of the thermal shrinkable tube 25 by apredetermined length L2, shown in FIG. 13. The base end of the couplingcomponent 31 is secured to one end of the thermal shrinkable tube 25 inthis positioning state.

When end portions of the thermal shrinkable tube 25 and the core rod 27are press-fitted, adhered, or deposited to the coupling component 31,this coupling component 31 is fixed integrally to the thermal shrinkabletube 25 and the core rod 27.

As shown in FIG. 13, in the coupling component 31, an end portion on theoptical connector ferrule 7 side is shaped into a cylinder portion 31 athat is fitted onto the base end of the optical connector ferrule 7. Anengaging hole 31 b with which the sleeve coupling projection 7 c of theoptical connector ferrule 7 is engaged is formed in this cylinderportion 31 a.

One end of the protection sleeve 15 is coupled integrally with theoptical connector ferrule 7 by engaging the sleeve coupling projection 7c with the engaging hole 31 b.

When the optical connector 1 is assembled, the coated optical fiber 3 ispassed previously through the protection sleeve 15 as well as the rearhousing 18 and the boot 21, as shown in FIG. 15( b), and the protectionsleeve 15 is replaced on the coated optical fiber 3 after the coatedoptical fiber 3 and the short optical fiber 5 are fusion-spliced. Then,length dimensions of the short optical fiber 5 and the protection sleeve15 are set with respect to the thermal shrinkable tube 25, the core rod27, and the adhesive tube 29 such that the fusion spliced portion 13 ispositioned just in an almost middle position of the protection sleeve 15in the longitudinal direction when the coupling component 31 is coupledto the base end of the optical connector ferrule 7.

In more precisely speaking, the protection sleeve 15 is moved onto thefusion spliced portion 13 to cover the fusion spliced portion 13 afterthe short optical fiber 5 and the coated optical fiber 3 arefusion-spliced, then the coupling component 31 of the protection sleeve15 is coupled to the optical connector ferrule 7, and then the coatedoptical fiber 3 and the short optical fiber 5 around the fusion splicedportion 13 are secured along the core rod 27 longitudinally by heatingthe thermal shrinkable tube 25.

In the case of the present embodiment, diameter dimensions of thecoupling component 31, the core rod 27, and the like are set such thatfiber positions of the short optical fiber 5 and the coated opticalfiber 3 being arranged in the protection sleeve 15 agree with an axiscenter of the optical connector ferrule 7 in a state that the thermalshrinkable tube 25 has been thermally shrunk.

The rear housing 18 is a cylindrical structural body for covering thecircumference of the protection sleeve 15, and is formed by the resininjection molding, or the like. A top end of the rear housing 18 isshaped into a cylinder portion 18 a that is fitted onto the base end ofthe plug frame 9. Then, an engaging hole 18 b that engages with anengaging claw (not shown) formed on the outer periphery of the based endof the plug frame 9 to project when this cylinder portion 18 a is fittedonto the base end of the plug frame 9 is provided to this cylinderportion 18 a.

The above rear housing 18 is put on the protection sleeve 15 after thethermal shrinking process of the protection sleeve 15. Then, the rearhousing 18 is coupled integrally to the plug frame 9 when the engaginghole 18 b on the top end side is engaged with the engaging claw of theplug frame 9.

In the case of the present embodiment, the SC connector knob 33 servingas a knob portion in the connector connection is put/fitted on the outerperiphery of the plug frame 9 to which the rear housing 18 is coupled.This SC connector knob 33 is the enclosure member that provides anexternal appearance of the optical connector 1 on the top end side. Anon-slip serrated portion 33 a for easy grasping is formed on the outersurface of the SC connector knob 33.

The boot 21 protects the coated optical fiber 3 such that a sharpbending is not applied to the coated optical fiber 3 that extended tothe rear side of the rear housing 18. The boot 21 is coupled integrallywith the rear housing 18 when its top end is tightly fitted to orscrewed into the base end of the rear housing 18.

Alternatively, the boot may be formed integrally with the rear housing18 by injection molding of a resin.

In the case of the present embodiment, as shown in FIG. 16, a space 35for enabling the protection sleeve 15 to retreat is created betweenother end 15 a of the protection sleeve 15 and an inner wall end 21 a ofthe boot 21 opposing to this other end 15 a.

Further, as shown in FIG. 12 and FIG. 16, a reinforcing tube 37 that isput on the coated optical fiber 3 is inserted/fitted to the back of theinner wall end 21 a of the boot 21.

A disconnection-preventing portion 37 a whose diameter is enlarged isprovided to the top end of the reinforcing tube 37. A backward movementof the boot 21 is restricted when the disconnection-preventing portion37 a is latched. The reinforcing tube 37 is a tube that has an adequateelasticity and prevents that the coated optical fiber 3 is bent sharply.

Next, a method of assembling the optical connector 1 shown in FIG. 16 byusing the holder 51 and the fusion splicing apparatus 71 explained abovewill be explained hereunder.

In this assembling method, as shown in FIG. 15( a), the holder 51 inwhich the connector plug 10 is housed is prepared previously. Also, asshown in FIG. 15 (b), the coated optical fiber 3 in the field is passedthrough the protection sleeve 15, the rear housing 18, and the boot 21.

Then, as shown in FIG. 8, a step of setting the coated optical fiber 3on the fiber fitting portion 78 of the fusion processing portion 74 inthe fusion splicing apparatus 71 and a step of setting the short opticalfiber 5 in which the connector plug 10 is housed on the holder fittingportion 73 of the fusion processing portion 74 are executed.

Then, the short optical fiber 5 positioned in the holder 51 being fittedto the holder fitting portion 73 and the coated optical fiber 3positioned on the fiber fitting portion 78 are fusion-spliced to eachother in the fusion processing portion 74.

Then, the fusion spliced portion 13 is formed by fusion-splicing theshort optical fiber 5 and the coated optical fiber 3, and then theconnector plug 10 is taken out from the holder 51. Then, as shown inFIG. 15( c), the protection sleeve 15 having the thermal shrinkable tube25 is put on the fusion spliced portion 13, and the coupling component31 formed on one end of the protection sleeve 15 is coupled to the plugframe 9. Thus, a step of obtaining a sleeve-plug coupled body 16 inwhich one end of the protection sleeve 15 is coupled to the plug frame 9is carried out.

Also, the sleeve-plug coupled body 16 is transferred to the firstthermal shrinkage processing portion 86 of the thermal shrinkageprocessing portion 76, and the thermal shrinkable tube 25 of theprotection sleeve 15 is thermally shrunk. Thus, a step of obtaining astructural body 19 in which the fusion spliced portion 13 is reinforcedby the thermal shrinkable tube 25 being shrunk, as shown in FIG. 15( d),is carried out.

Then, the rear housing 18 and the boot 21 through which the coatedoptical fiber 3 is passed previously are coupled to the plug frame 9 ofthe structural body 19. Thus, a completed structure shown in FIG. 15( e)can be obtained.

According to the above optical connector assembling method, the opticalconnector 1 can be assembled effectively by using the holder 51 and thefusion splicing apparatus 71 without damage of the optical connectorferrule 7 and the short optical fiber 5.

Next, a third embodiment of the holder and the fusion splicing apparatusaccording to the present invention will be explained hereunder.

First, prior to explanation of the holder and the fusion splicingapparatus, the optical connector used in the holder of the presentembodiment will be explained hereunder.

FIG. 17 is an exploded side view of an optical connector used in thethird embodiment of the present invention. In this case, in the presentembodiment, explanation will be made by affixing the same symbols to thesame member and the same portion in the above embodiment.

The optical connector can be applied to both the fiber cord type towhich an optical fiber cord 70 is connected and the coated fiber type towhich the coated optical fiber 3 is connected. The coated fiber typeoptical connector uses substantially common components to the fiber cordtype optical connector except that a shape of the Sc connector knob isslightly different. In the following explanation, mainly a fiber cordtype optical connector (referred simply to as an “optical connector”hereinafter) 1B will be explained.

The optical connector 1B has an Sc connector knob 181, a plug frame 183,a fiber built-in ferrule (optical connector ferrule) 185, a protectionsleeve 187, a ferrule set spring 189, a rear housing 191, a caulkingring 193, and a boots 195 as major members from the top end side (theleft side in FIG. 18) to which the counter side optical connector iscoupled. That is, the structure in which the stopper 11 and the couplingcomponent 31 explained in the above embodiment are not used is shown.

FIG. 18( a) is a longitudinal sectional view of the optical connectorshown in FIG. 17, and FIG. 18 (b) is a longitudinal sectional view of apertinent portion of a variation in which a reinforcing tube is fitted.

The optical connector ferrule 185 is constructed by fitting andiameter-enlarged portion 7 b whose outer diameter is enlarged to theback side of a top end shaft portion 7 a to which the optical connecterferrule on the other side is butted and connected, and the short opticalfiber 5 is fitted to the optical connector ferrule 185 such that itscenter axis is aligned with the top end shaft portion 7 a. Also, asleeve coupling projection 7 c to which the protection sleeve 187described later is coupled is provided to an outer periphery of theoptical connector ferrule 185 on the base end side from which the shortoptical fiber 5 is extended.

When the optical connector ferrule 185 inserted into an opening of theplug frame 183 on the base end side, the diameter-contracted portion 9 aprovided to an inner periphery of the plug frame 183 to protrude isbrought into contact with the front end of the diameter-enlarged portion7 b, as shown in FIG. 19, and thus a forward movement of this ferrule185 is restricted. In this state, a position of the optical connectorferrule 185 is fixed in the position that the top end of the opticalconnector ferrule 185 protrudes from the top end of the plug frame 183by a predetermined length L1.

In order to prevent adhesion of the dust, etc. to a fiber end surfaceduring the storage, the dust cap 22 (see FIG. 2) is put on a top end ofthe optical connector ferrule 185 that has been positioned in the plugframe 183.

In this case, the top end surface of the optical connector ferrule 185is mirror-polished previously to omit the polishing on the job site.

The ferrule set spring 189 is inserted in the plug frame 183 into whichthe optical connector ferrule 185 is inserted. This ferrule set spring189 is a compression coil spring that is put and held between the rearhousing 191, which is engaged with the plug frame 183 and describedlater, and the diameter enlarged portion 7 b of the optical connectorferrule 185. The ferrule set spring 189 brings the diameter-enlargedportion 7 b of the optical connector ferrule 185 into contact with theabove diameter-contracted portion 9 a of the plug frame 183, and alsoelastically support the diameter-enlarged portion 7 b retractably.

FIG. 19 (a) is a sectional view of an optical connector ferrule shown inFIG. 20, and FIG. 19( b) is a longitudinal sectional view of a thermalshrinkable tube connected to the optical connector ferrule.

The fusion spliced portion 13 is formed by butting an end portion 5 b,from which a coating 5 a is striped off, of the short optical fiber 5and an end portion 3 b, from which a coating 3 a is striped off, of thecoated optical fiber 3 and then fusing the mutual butted fiber endsurfaces.

In this case, the end surface of the short optical fiber 5, from whichthe coating 5 a is striped off, is mirror-processed previously by eitherthe cleavage caused when the optical fiber is cut by applying a bendingstress to this fiber or the polishing to neglect the mirror processingon the job site.

Also, preferably an edge of the end surface of the short optical fiber 5should be chamfered by the electrical discharge process prior to thefusion splicing, for the chipping generated from the edge by thepolishing can be prevented. Also, preferably the carbon coated fibershould be employed as the short optical fiber 5, for a reduction ofstrength caused due to a scratch or a moisture absorption generated incarrying the optical fiber in a coating removed state to the job sitecan be suppressed. Also, preferably the short optical fiber 5 should beformed of the fiber that is strong against the bending having a smallMFD.

As shown in FIG. 19, the protection sleeve 187 is equipped with thethermal shrinkable tube 25 and the core rod 27 and the adhesive tube(see FIG. 14) that are inserted into the thermal shrinkable tube 25. Thethermal shrinkable tube 25 is coupled to the optical connector ferrule185. The coated optical fiber 3 is fitted into the optical connector 1Bin a state that an outer coating 72 is removed from the end portion ofthe optical fiber cord 70 by a predetermined length. The protectionsleeve 187 covers the outer periphery of the coated optical fiber 3 onthe other end side where this fiber is not coupled to the opticalconnector ferrule 185.

The thermal shrinkable tube 25 thermally shrinks when it is heated at apredetermined temperature by the heating machine, and is tightly adheredto the core rod 27 that is inserted into this tube.

The adhesive tube 29 is softened by the heating applied when the thermalshrinkable tube 25 is cause to thermally shrink, and acts as theadhesive to bury a clearance 34 between the thermal shrinkable tube 25and the core rod 27.

The thermal shrinkable tube 25, the core rod 27, and the adhesive tube29 are positioned with respect to one end of the protection sleeve 187such that the end portion of the core rod 27 is aligned with the endportion of the adhesive tube 29. Then, the protection sleeve 187 issecured to the sleeve coupling projection 7 c of the optical connectorferrule 185 under this positioned condition.

When the end portions of the thermal shrinkable tube 25 and the core rod27 are press-fitted or adhered or deposited to the optical connectorferrule 185, this optical connector ferrule 185 is fixed/integrated withthe tube 25 and the core rod 27.

Respective length dimensions of the short optical fiber 5 and thethermal shrinkable tube 25, the core rod 27 and the adhesive tube 29 ofthe protection sleeve 187 are set such that, when the protection sleeve187 is coupled to the sleeve coupling projection 7 c on the base end ofthe optical connector ferrule 185, the fusion spliced portion 13 can bejust positioned in an almost middle position of the protection sleeve187 in the length direction.

After the short optical fiber 5 and the coated optical fiber 3 arefusion-spliced, the protection sleeve 187 is moved to cover the fusionspliced portion 13 and to contact the optical connector ferrule 185.Then, the coated optical fiber 3 and the short optical fiber 5 are fixedby applying a heat to the thermal shrinkable tube 25 in a state thatthey are positioned vertically along the core rod 27.

In this manner, dimensions of respective components are set such that,when the thermal shrinkable tube 25 is cause to thermally shrink, theend portion of the thermal shrinkable tube 25 overlaps with the coating3 a of the coated optical fiber 3 and the sleeve coupling projection 7 cby 2 mm or more.

The rear housing 191 is a cylindrical structural body for covering theperiphery of the protection sleeve 187, and is formed by the resininjection molding, or the like. A top end of the rear housing 191 isshaped into a cylinder portion 191 a that is fitted into the base end ofthe plug frame 183. An engaging claw 191 b for engaging with an engaginghole 183 a formed on the outer periphery on the base end of the plugframe 183 when the rear housing 191 is fitted into the base end of theplug frame 183 is provided to this cylinder portion 191 a.

The above rear housing 191 is moved on the protection sleeve 187 and putthereon after the thermal shrinkage process of the protection sleeve187. Then, the rear housing 191 is coupled integrally with the plugframe 183 by engaging the engaging claw 191 b on the top end side withthe engaging hole 183 a of the plug frame 183.

An SC connector knob 181 serving as a knob portion when the connector iscoupled is put/fitted to the outer periphery of the plug frame 183 towhich the rear housing 191 is fitted. This SC connector knob 181 is anouter fitting member that provides an external appearance of the opticalconnector 1B on the top end side. A non-slip serrated pattern 33 a foreasy grasping is formed on the outer side surface of this knob.

The boots 195 protects the optical fiber cord 70 not apply a sharpbending to the optical fiber cord 70 that extends to the rear side ofthe rear housing 191. When a top end of the boots 195 is fitted to orscrewed into the base end of the rear housing 191, the boots 195 iscoupled integrally to the rear housing 191.

In this case, the boots 195 may be formed integrally with the rearhousing 191 by the resin injection molding.

The space 35 (see FIG. 18) for allowing retreat of the protection sleeve187 is formed between the other end 187 a (see FIG. 19) of theprotection sleeve 187 and the inner wall end opposing to this other end187 a in the boots 195.

In this case, as shown in FIG. 18( b), the boots 195 may have such astructure that the reinforcing tube 37 that is put on the optical fibercord 70 is inserted/fitted to the rear side of the inner wall end.

A slip-off preventing portion 37 a whose diameter is expanded toward thetop end is provided to the reinforcing tube 37. When the slip-offpreventing portion 37 a is latched on the inner wall end of the boots195, its backward movement is restricted. The reinforcing tube 37 is atube having an adequate elasticity to prevent that the optical fibercord 70 is bent sharply.

In the optical connector 1B, the outer coating 72 is stripped offlargely from the end portion of the optical fiber cord 70 to provide thegood fusion splicing operation when the short optical fiber 5 of theoptical connector ferrule 185 is fusion-spliced to the coated opticalfiber 3 being exposed by removing the outer coating 72 of the opticalfiber cord 70 on the job site. The coated optical fiber 3 whose outerperiphery is covered with a high tensile fiber (Kevlar) 174 is exposedfrom the optical fiber cord 70 when the outer coating 72 is stripped off(removed) from the end portion.

The high tensile fiber 174 and the outer coating 72 are cut in apredetermined length, and inserted on a rear end portion 191 c of therear housing 191. The caulking ring 193 is put on the outer periphery ofthe outer coating 72, and the caulking ring 193 is caulked to reduce thediameter. Since the diameter of the caulking ring 193 is reduced, theouter coating 72 and the high tensile fiber 174 are press-fitted intothe caulking ring 193 and the rear end portion 191 c and secured to therear housing 191.

Next, the holder according to the present embodiment will be explainedhereunder.

FIG. 20 is a perspective view of a third embodiment of the holderaccording to the present invention, FIG. 21 is a plan view showing astate that a lid member of the holder shown in FIG. 20 is closed, andFIG. 22 is a front view of the holder shown in FIG. 21.

A holder 151 of the third embodiment holds the optical connector ferrule185 (see FIG. 17) in a state that the dust cap 22 is put, and protectsthe optical connector ferrule 185.

In the holder 151 of the present embodiment, a foldable lid member 156is provided to a holder main body 154 in which a ferrule containingportion 153 as the recess for containing the optical connector ferrule185 is formed to open upward. This lid member 156 covers the ferrulecontaining portion 153, and presses the optical connector ferrule 185contained in the ferrule containing portion 153.

The box-like cap 57 (see FIG. 2) is detachably coupled to the front endside of the holder main body 154 from which the short optical fiber 5extends. The box-like cap 57 covers the periphery of the short opticalfiber 5 extended from the holder main body 154 to protect the shortoptical fiber 5.

The cap 57 should be formed of the antistatic material.

The lid member 156 is hinged to the side portion of the holder main body154 around a turning/supporting shaft 158 being fitted to the sideportion of the holder main body 154. The lid member 156 is opened/closedin the arrow c direction shown in FIG. 20 based on the turning operationaround the turning/supporting shaft 158.

The lid member 156 is shaped into an almost flat plate that is put onthe holder main body 154. As shown in FIG. 20, a grasping portion 156 athat the worker grasps by fingers in opening/closing operations isprojected from its one side portion.

Also, as shown in FIG. 21, a front end portion 156 b of the lid member156 is formed such that the operator can view the base end portion andits neighborhood of the optical connector ferrule 185 contained in theholder main body 154.

As shown in FIG. 22, in the holder 151 of the present embodiment, arecess portion 161 is provided to an upper end surface of a front endwall 154 a of the holder main body 154. This recess portion 161 is usedto position/support the sleeve coupling projection 7 c of the opticalconnector ferrule 185. The short optical fiber 5 protrudes coaxiallyfrom the sleeve coupling projection 7 c, as described above.

Also, as shown in FIG. 22, the lid member 156, when closed,presses/holds the optical connector ferrule 185 via the dust cap 22 andthus positions the sleeve coupling projection 7 c in the recess portion161. In this case, it is of course that the lid member 156 may be formedto directly press/hold the optical connector ferrule 185. Also, a lengthof the ferrule containing portion 153 in the axial direction is almostequal to a length from a front end of the diameter-enlarged portion 7 bof the optical connector ferrule 185 to a rear end of the dust cap 22.Accordingly, the optical connector ferrule 185 on which the dust cap 22is put is housed without the play in the axial direction. In this holder151, when the front end of the diameter-enlarged portion 7 b is broughtinto contact with the front inner wall of the ferrule containing portion153, a projection length L2 (see FIG. 21) of the short optical fiber 5is set to about 10 mm. That is, a relative position of the short opticalfiber 5 to the holder 151 is decided.

When the holder 151 is fitted to a fusion splicing apparatus 171 thatfusion-splices other coated optical fiber 3 (see FIG. 23) on the jobsite, described later, the short optical fiber 5 protruded from theoptical connector ferrule 185 that is contained in the ferrulecontaining portion 153 is positioned in the fusion splicing position asit is.

According to the holder 151 of the third embodiment explained as above,when the optical connector ferrule 185 to which the short optical fiber5 is fitted in advance is contained in the holder 151 and the cap 57 isput thereon, the holder 151 protects the optical connector ferrule 185and the short optical fiber 5 from the impact, etc. applied from theoutside.

In addition, the holder 151 can position the short optical fiber 5 whilecontaining the optical connector ferrule 185 as it is in the fusionsplicing position of the fusion splicing apparatus 171. Therefore, theholder 151 can improve the handling property in the fusion splicingoperation.

Also, only when the holder 151 is fitted to the fusion splicingapparatus 171, there is no need to prepare the dedicated fusion splicingapparatus for connecting the existing coated optical fibers mutually.

Also, the recess portion 161 for positioning/supporting the extendedshort optical fiber 5 is provided to the holder 151 of the presentembodiment. The short optical fiber 5 protruded from the opticalconnector ferrule 185 that is contained in the holder 151 is positionedprecisely on the holder 151. Therefore, when the holder 151 is set inthe fusion splicing apparatus 171, a time and labor required forpositioning the short optical fiber 5 is not needed.

Also, the holder 151 of the present embodiment is constructed such thatthe lid member 156 for pressing the optical connector ferrule 185 beingcontained in the ferrule containing portion 153 is provided to theholder main body 154 in which the ferrule containing portion 153 thatcontains the optical connector ferrule 185 therein is formed to openupwardly. Therefore, the optical connector ferrule 185 can be easily putin or taken out from the holder 151 by opening/closing the foldable lidmember 156.

Also, the short optical fiber 5 extended from the optical connectorferrule 185 that is housed in the holder main body 154 is positioned bythe recess portion 161, and then the optical connector ferrule 185 isfixed by the lid member 156. Therefore, the positioning of the shortoptical fiber 5 can be executed without fail.

Also, the front end portion 156 b through which the base end portion andits neighborhood of the optical connector ferrule 185 can be viewed isformed in the lid member 156. Therefore, the operator can check thecontained state, the type, etc. of the contained optical connectorferrule 185 not to open the lid member 156.

In this embodiment, in order to make it easy to view the opticalconnector ferrule 185 contained in the holder main body 154, the frontend portion 156 b is provided to the lid member 156. Alternately, thelid member 156 may be formed of the transparent material in place of theformation of the front end portion 156 b. Even when the lid member 156is formed of the transparent material in this manner, the operator cancheck the contained optical connector ferrule 185 with the eyes not toopen the lid member 156.

Next, an embodiment of the fusion splicing apparatus using the holder151 will be explained hereunder.

FIG. 23 is a perspective view of a fusion splicing apparatus accordingto the present embodiment when viewed from the obliquely above side, andFIG. 24 is an enlarged view of the fusion splicing apparatus in FIG. 23in a state that a cover of a thermal shrinkage processing portion isremoved.

The fusion splicing apparatus 171 is the apparatus that fusion-splicesthe short optical fiber 5 fitted previously to the optical connectorferrule 185 to other coated optical fiber 3 on the job site where theoptical fiber provision work is carried out.

This fusion splicing apparatus 171 is equipped with a fusion processingportion 174 and a thermal shrinkage processing portion 176. This fusionprocessing portion 174 is equipped with a holder fitting portion 173that positions the short optical fiber 5 in a fusion splicing positionto other coated optical fiber 3 by fitting the short optical fiber 5contained in the above holder 151 together with the holder. This thermalshrinkage processing portion 176 causes the thermal shrinkable tube 25,which is put on the outer periphery of the fusion spliced portion 13(see FIG. 19) between the short optical fiber 5 and other coated opticalfiber 3 both being fusion-spliced by the fusion processing portion 174,to shrink by the heater.

Normally the fusion processing portion 174 is provided to the uppersurface portion of the apparatus that is covered with a foldable cover177.

As shown in FIG. 24, the fusion processing portion 174 includes a fiberfitting portion 178 to which other coated optical fiber 3 is set on thejob site, the V-groove member 79 arranged at the top end of the fiberfitting portion 178 to position a top end position of the coated opticalfiber 3 being set in the fiber fitting portion 178, the V-groove member81 for positioning a top end position of the short optical fiber 5extended from the holder 151 being set in the holder fitting portion173, and the electrode 83 arranged between a pair of V-groove members79, 81 to fusion-splice the mutually butted fibers by the discharge.

Respective dimensions of the V-groove member 81 for positioning theshort optical fiber 5 and the recess portion 161 of the holder 151 beingset in the holder fitting portion 173 are set such that theysupport/position the short optical fiber 5 on a straight line.

The holder fitting portion 173 may be equipped previously with theholder. In this case, the optical connector ferrule 185 housed inanother case is picked up and then is housed in the holder 151 being setin the holder fitting portion 173.

The thermal shrinkage processing portion 176 has a dedicatedopening/closing cover 184, and is equipped adjacent to the fusionprocessing portion 174.

As shown in FIG. 24, a thermal shrinkage processing portion 186 isprovided when the opening/closing cover 184 is opened.

The thermal shrinkage processing portion 186 is equipped with a heatingportion 88 in which a heater (not shown) for heating the thermalshrinkable tube 25 is provided, a ferrule fitting portion 189 forpositioning the optical connector ferrule 185 taken out from the holder151 and fitting it, and a fiber fitting portion 90.

A foldable cover 91 for pressing a jumping-out of the coated opticalfiber is fitted to the ferrule fitting portion 189 and the fiber fittingportion 90.

A heating temperature distribution of the heater is set in the thermalshrinkage processing portion 186 such that a heating temperature on theshort optical fiber 5 side of the thermal shrinkable tube 25 is sethigher than that on the coated optical fiber 3 side.

The thermal shrinkage processing portion 186 has the configuration thatis suitable for the protection sleeve 187 in which the end portion ofthe thermal shrinkable tube 25 is connected to the sleeve couplingprojection 7 c of the optical connector ferrule 185. Since the heatingtemperature distribution is provided to the heater such that first theshort optical fiber 5 side is heated at a high temperature to shrink andthen the coated optical fiber 3 side is caused to shrink, a vaporgenerated due to the shrinkage and remaining in the thermal shrinkabletube 25 is ready to escape from the end portion of the coated opticalfiber 3 side.

The fusion splicing apparatus 171 explained above is equipped with thefusion processing portion 174 to which the holder fitting portion 173 towhich the holder 151 containing the optical connector ferrule 185 isfitted is provided. Therefore, the short optical fiber 5 fitted to theoptical connector ferrule 185 and other coated optical fiber 3 can befusion-spliced mutually not to pick up the optical connector ferrule 185from the holder 151, and operability in the fusion splicing operationcan be improved.

In respective embodiments of the holder, the lid member is provided tothe holder main body. But the foldable cover of the fusion splicingapparatus may be used commonly as this lid member.

Next, an assembling method of the optical connector 1B shown in FIG. 17by using the holder 151 and the fusion splicing apparatus 171 will beexplained-hereunder.

In this assembling method, the holder 151 containing the opticalconnector 1B and shown in FIG. 21 is prepared previously. Also, thecoated optical fiber 3 on the job site are inserted into the protectionsleeve 187, the rear housing 191, and the boots 195.

Then, as shown in FIG. 23, the step of setting the coated optical fiber3 in the fiber fitting portion 178 of the fusion processing portion 174of the fusion splicing apparatus 171 and the step of setting the holder151 in which the optical connector ferrule 185 is housed to the holderfitting portion 173 of the fusion processing portion 174 are carriedout.

Then, the short optical fiber 5 positioned in the holder 151 fitted tothe holder fitting portion 173 and the coated optical fiber 3 positionedin the fiber fitting portion 178 are fusion-spliced in the fusionprocessing portion 174.

Then, the fusion spliced portion 13 is formed by fusion-splicing theshort optical fiber 5 and the coated optical fiber 3, and then theoptical connector ferrule 185 is taken out from the holder 151. Then, asshown in FIG. 24, the steps of obtaining a ferrule/sleeve coupled body201 by moving the protection sleeve 187 having the thermal shrinkabletube 25 onto the fusion spliced portion 13 and then inserting the sleevecoupling projection 7 c of the optical connector ferrule 185 into oneend of the protection sleeve 187 are carried out.

Also, the ferrule/sleeve coupled body 201 is transferred to the thermalshrinkage processing portion 186 to cause the thermal shrinkable tube 25of the protection sleeve 187 to thermally shrink. Thus, as shown in FIG.19, the steps of obtaining the structure in which the fusion splicedportion 13 is reinforced by the thermal shrinkable tube 25 are carriedout.

Then, a completed structure shown in FIG. 18 is obtained by coupling theplug frame 183 and the rear housing 191 and the boots 195, through whichthe coated optical fiber 3 is passed previously, to the opticalconnector ferrule 185 built up as the structure.

According to the above optical connector assembling method, the opticalconnector 1B can be assembled effectively by using the holder 151 andthe fusion splicing apparatus 171 without any damage of the opticalconnector ferrule 185 and the short optical fiber 5.

The present invention is explained in detail with reference to theparticular embodiments. But it is apparent for those skilled in the artthat various variations and modifications can be applied withoutdeparting from a spirit and a scope of the present invention.

This application is based upon Japanese Patent Application (PatentApplication No. 2006-307142) filed Nov. 13, 2006; the contents of whichare incorporated herein by reference.

INDUSTRIAL APPLICABILITY

The holder can protect the optical connector ferrule and the shortoptical fiber from the impact, etc. from the external cause if theconnector plug having the optical connector ferrule is housed therein.

In addition, this holder can position the short optical fiber fitted tothe optical connector ferrule in the fusion position of the fusionsplicing apparatus. Therefore, the troublesome operation for picking upthe connector plug from the holder in the fusion splicing operation canbe omitted, and the handling property in the fusion splicing operationcan be improved.

Also, the short optical fiber fitted to the optical connector ferruleand other coated optical fiber can be fusion-spliced not to take out theconnector plug from the holder. Thus, the operability of the fusionsplicing operation can be improved.

Also, when the thermal shrinkage processing portion for causing thethermal shrinkable tube to thermally shrink is provided in parallel withthe fusion processing portion, thermal shrinkage process of the thermalshrinkable tube can be executed not to take out the connector plug fromthe holder.

Further, the optical connector assembling method can assemble theoptical connector effectively by using the above holder and the abovefusion splicing apparatus without any damage of the optical connectorferrule and the short optical fiber.

1. A holder for containing an optical connector ferrule to which a shortoptical fiber is fitted, wherein the holder is constructed to positionthe short optical fiber extended from the optical connector ferrule andto be fitted to a fusion splicing apparatus that fusion-splices theshort optical fiber and other coated optical fiber.
 2. A holderaccording to claim 1, wherein a recess portion for positioning the shortoptical fiber extended from the optical connector ferrule is provided.3. A holder according to claim 1, wherein a lid member for pressing theoptical connector ferrule is provided to a holder main body in which aferrule containing portion for containing the optical connector ferruleis formed.
 4. A holder according to claim 3, wherein the lid member isformed of transparent material.
 5. A holder according to claim 1,wherein the optical connector ferrule to which the short optical fiberis fitted is contained in a mode of a connector plug whose outerperiphery is covered with a plug frame.
 6. A holder according to claim5, wherein a V groove for positioning the short optical fiber extendedfrom the plug frame is provided.
 7. A holder according to claim 5,wherein a lid member for pressing the plug frame is provided to a holdermain body on which a plug housing portion for housing the plug frametherein is formed.
 8. A holder according to claim 7, wherein the lidmember is formed of a transparent material.
 9. A holder according toclaim 7, wherein the lid member presses the short optical fiberpositioned on the V groove.
 10. A fusion splicing apparatus forfusion-slicing a short optical fiber fitted to an optical connectorferrule and other coated optical fiber, comprising: a fusion processingportion equipped with a holder fitting portion that fits the holder setforth in claim
 1. 11. A fusion splicing apparatus according to claim 10,further comprising: a thermal shrinkage processing portion forheating/shrinking a thermal shrinkable tube that is put on an outerperiphery of a fusion spliced portion being formed by the fusionprocessing portion; wherein the thermal shrinkage processing portion isequipped with a holder fitting portion that fits the holder.
 12. Afusion splicing apparatus according to claim 11, wherein the thermalshrinkage processing portion has a first thermal shrinkage processingportion in which a heating temperature distribution is set such that aheating temperature of the thermal shrinkable tube on the short opticalfiber side is higher than that on the coated optical fiber side.
 13. Afusion splicing apparatus according to claim 12, wherein the thermalshrinkage processing portion has a second thermal shrinkage processingportion in which a heating temperature distribution is set such that aheating temperature of the thermal shrinkable tube on a middle portionside is higher than that on an end portion.
 14. An optical connectorassembling method of assembling an optical connector in which othercoated optical fiber is fusion-spliced to a short optical fiber, byfusion-splicing the short optical fiber being fitted to an opticalconnector ferrule to the other coated optical fiber while using thefusion splicing apparatus set forth in claim 10, comprising; a step ofsetting the coated optical fiber on a fiber fitting portion of a fusionprocessing portion of the fusion splicing apparatus; a step of setting aholder that holds the optical connector ferrule therein in a holderfitting portion of the fusion processing portion; a step offusion-splicing the short optical fiber positioned in the holder that isfitted to the holder fitting portion and the coated optical fiberpositioned in the fiber fitting portion in the fusion processingportion; a step of forming a fusion spliced portion by fusion-splicingthe short optical fiber and the coated optical fiber, and then putting aprotection sleeve having a thermal shrinkable tube on the fusion splicedportion; and a step of transferring the fusion spliced portion to athermal shrinkage processing portion, and then heating the thermalshrinkable tube of the protection sleeve to shrink.